I often am accused of “not liking” dark-roasted coffee. Whereupon I try to explain that what I don’t like are bad dark roasts: thin-bodied, burned dark roasts. Tactfully developed dark roasts, those in which the sugars have been caramelized rather than burned and in which enough fat survives to smooth the cup, are fine with me. And if some nuance also survives, or better yet, transforms in some interesting way under the impact of the roast, so much the better.

The problem may be that many coffee lovers, and even a few coffee professionals, don’t understand that, at least up to a point, it’s not how dark you roast the coffee, it’s how you roast it dark. You can roast it slowly and sensitively, keeping the temperatures in the roasting chamber from escalating at the end of the roast, or you can, essentially, burn it and destroy it.

I admit that I do have difficulty appreciating “French roast” blends, the consensus name for blends brought to the very most extreme dark end of the roast spectrum. No matter how skillful the roastmaster, very little tends to survive with these roasts except a rather thin-bodied bittersweet sensation.

There is, of course, something attractive in the right kind of burned taste. And certainly bitter combined with sweet is a paradox that runs pleasurably through human cuisine, from sweet-and-sour East Asian dishes to Campari to bittersweet chocolate. But I often wonder whether people who buy French roasts wouldn’t be happier with roasts that are a little less extreme, and preserve a bit more sweetness, brightness, and nuance to go with the bitter tones. Perhaps they don’t understand what to ask for, and buy “French roast” because they’re not fully aware of the range of possibility on the dark end of the spectrum and don’t have names for those possibilities.

At any rate, such are the thoughts behind this month’s cupping. I cupped eight extremely dark French roasts to see if I could pick up any interesting differences among them, then matched the French roasts with an array of coffees brought to less-than-extreme degrees of darkness. I chose coffees from West-Coast companies partly because the West Coast, in the person of Alfred Peet and some North Beach San Francisco roasters, established the contemporary taste for dark roasts. Generally I reported on two coffees from each roaster. In single origins I leaned toward East Africa when I had a choice, since the distinctive East Africa profiles tend to maintain their individuality in a dark roast better than most other origins.

Unfortunately, there were no real surprises with the eight “French-roast” blends. Whether owing to the extremely dark roast, to the blend formula, or to both, I found it difficult to tell these darkest-of-dark coffees apart. They displayed some minor nuance in aroma, but in the cup all that remained were variations of sweet and bitter sensation, abstract and fundamental, without aromatic modulation. Some were a bit more intense in their bittersweetness than others, some were almost entirely bitter with little sweetness, some were sweeter, and one or two displayed faint spicy notes. I decided to report on the two that seemed the best and most interesting, and allow the other six to remain anonymous.

Two of the other dark-roast blends I chose, Fogbuster from Jeremiah Pick and Italian Roast from Starbucks, turned out to be French roasts under another name, very darkly roasted and only slightly more complex in the cup than their Gallic-named counterparts. However, the six remaining coffees were another story. Some were splendid, and all were worthy and interesting. In most cases the sweet side of the bittersweet equation was complex and lively rather than monotonal, and the bitterness tended to support the profile rather than dominate it, as it often did in the French-roast blends. I find it hard to imagine that someone who buys one of the French roasts wouldn’t be better served by a coffee like the Pannikin Turkish Blend, which keeps the bitter taste as foundation but adds an exquisitely fruity complexity, or the Peet’s Kenya, where the bitter, roast-driven pungency is almost indescribably rich and carnal.

A note on the mysterious numbers that appear after the “Roast” description. These numbers represent degree or darkness of roast as measured by a specially modified spectrophotometer popularly called an “Agtron” after the name of the best-known manufacturer of these instruments. Agtron numbers are a way of measuring certain near-infrared wavelengths not visible to the human eye. The Agtron manufacturer contends, and most coffee-cuppers agree, that these wavelengths are a good indicator of degree or darkness of roast. The smaller the Agtron number the darker the roast. The lightest palatable roast measures about 95; the darkest somewhere around the 17 or 18 mark registered here by the Jeremiah’s Pick Fogbuster blend. In my experience, and as confirmed by this cupping, the dividing line between dark roasts in which little aromatic nuance survives and those in which it does is about 25. In other words, below Agtron 25 you get the bittersweet-and-not-much-else kind of roasts often sold as “French”; above 25 you get the potential for more complexity and sweetness. Assuming, of course, that the roastmaster coddles the coffee and understands dark roasts. I have tasted dried-out, roast-ravaged coffees at levels much less dark than any represented in this cupping.

The Agtron number preceding the slash indicates the darkness of the coffee in whole-bean form; the number following the slash indicates the darkness of the coffee in ground form. The larger the difference between the two numbers the more likely the coffee embodies a wide range of roast taste.

Kenneth Davids is a coffee expert, author and co-founder of Coffee Review. He has been involved with coffee since the early 1970s and has published three books on coffee, including the influential Home Roasting: Romance and Revival, now in its second edition, and Coffee: A Guide to Buying, Brewing and Enjoying, which has sold nearly 250,000 copies over five editions. His workshops and seminars on coffee sourcing, evaluation and communication have been featured at professional coffee meetings on six continents.